Hatch in the tube, not the car.

Heh, look up "vacuum cannon" on youtube. The tunnel would need to be slowly depressurized, otherwise anything in it would turn into a bullet when the atmosphere rushes in.

This also applies to any sort of failure that compromises the vacuum. A dipshit with a rifle could kill anybody in the system in a fraction of a second. Burying the tubes is probably the only way to avoid this, but thankfully the whole thing is vaporware anyway.

You don't need a full vaccum. Even half an atmosphere would greatly reduce air resistance and allow for 4x the velocity in 1 atm.

Humans can survive (uncomfortably) at .5 atm and you eliminate the vacuum cannon problem simply by putting pressurization valves periodically throughout the tube.

The tube is vacuum, you'd need an airlock not just a simple hatch, no? How do passengers get from car to airlock without a suit?

Hyperloop is not a full vacuum, only partial vacuum if I'm not mistaken. I don't know what kind of difference that would make on pressure but I assume that means that the tubes are not air tight and actually breathe.

Hyper-loop requires 99.99% of the air to be removed from the tube, so it is complete vacuum from the lethality / safety and structure / pressure perspective.

I am not sure what do you mean by 'ubes are not air tight and actually breathe', but they definitely are not air permeable.

Depressurize the tube first.